Siloxane oligomers, a process for their production and their use

ABSTRACT

Siloxane oligomers of the general formula I or II  
                 
 
     wherein at least one functionalized alkyl group is present per oligomer molecule. The siloxane oligomers are produced by oligomerization of halogenalkyltrihalogensilanes, and co-optionally co-oligomerized with (C 1 -C 18 )-alkyl-, phenyl-, aryl- or aralkyl-trihalogensilanes and/or silicon tetrachloride, in the presence of alcohol and water, following which the halogenalkyl function is optionally modified in a further step. The siloxane oligomers can be used as coupling agents in rubber mixtures or as building preservation agents.

INTRODUCTION AND BACKGROUND

[0001] The present invention relates to siloxane oligomers, a processfor their production as well as their use.

[0002] It is known to employ silanes as coupling agents. Thus,aminoalkyltrialkoxysilanes, methacryloxyalkyltrialkoxysilanes,polysulfanalkyltrialkoxysilanes, as well asmercaptoalkyltrialkoxysilanes are used as coupling agents betweeninorganic materials (e.g. glass fibres, metals, oxidic fillers) andorganic polymers (e.g. thermosetting plastics, thermoplastic materials,elastomers) and/or as crosslinking agents and surface modificationagents.

[0003] These coupling or bonding agents form bonds with the filler aswell as the elastomer and thereby produce a good interaction between thefiller surface and the elastomer. They reduce the viscosity of themixture and facilitate the dispersion of the filler.

[0004] Furthermore it is known that the use of commercially availablesilane coupling agents (DE 22 55 577) with three alkoxy substituents onthe silicon atom leads to the release of considerable amounts of alcoholduring the mixing process.

[0005] This amount of alcohol can be reduced if corresponding siloxaneoligomers are used instead of monomeric silanes. Siloxane oligomers andsiloxane co-oligomers produced by condensation and co-condensation ofsilanes are described in EP 0 518 057 B1 and in EP-0 652 245 B1.

[0006] Disadvantages of the known siloxane oligomers are

[0007] the absence of functionalized alkyl groups, which are necessaryfor subsequent chemical reactions, and

[0008] the complicated process for the production of the alkoxysiloxanesby reacting the corresponding chlorosilanes with alcohol followed byremoval of the alcohol in the oligomerization or co-oligomerization withother alkoxysilanes.

[0009] An object of the present invention is to produce siloxaneoligomers having functionalized alkyl groups.

SUMMARY OF THE INVENTION

[0010] The above and other objects of the invention can be achieved bysiloxane oligomers of the formulae I or II

[0011] in which x denotes an integer from 0 to 1000, y denotes a numberfrom 1 to 1000, and the substituents R are identical or different andare members selected from the groups consisting of functionalized alkylgroups, (C₁-C₁₈) alkyl, (C₁-C₄)alkoxy, preferably methoxy or ethoxygroups, (C₁-C₄)haloalkoxy, phenyl, aryl, aralkyl and hydroxy groups,which are characterized in that at least one functionalized alkyl groupis present per oligomer molecule.

[0012] A maximum of one functionalized alkyl group per silicon atom canbe present.

[0013] The functionalized alkyl group can be a halogenated alkyl,aminoalkyl, methacryloxyalkyl, mercaptoalkyl, thiocyanatoalkyl orazidoalkyl group.

[0014] The functionalized alkyl group can be a disulfide bridge orpolysulfide bridge S_(x), where x is between 2 and 8, that joins twofunctionalized alkyl groups via the disulfide or polysulfide bridge.

DETAILED DESCRIPTION OF INVENTION

[0015] The siloxane oligomers according to the invention may be presentas individual compounds having a defined molecular weight as well as anoligomer mixture having a molecular weight distribution.

[0016] The invention also provides a process for the production of thesiloxane oligomers according to the invention, whereinhalogenalkyltrihalogensilanes are oligomerized in the presence ofalcohol and water and are optionally co-oligomerized with(C₁-C₁₈)-alkyl-, phenyl-, aryl- or aralkyl-trihalogensilanes and/orsilicon tetrachloride and the halogen alkyl function is optionallymodified in a further step.

[0017] Propanol, ethanol, methanol, diols or polyols may be used asalcohol.

[0018] (C₁-C₁₈)-alkyltrichlorosilanes, for example methyltrichlorsilane,ethyltrichlorsilane or propyltrichlorosilane, may be used asalkyltrihalogensilane.

[0019] The amount of water may be calculated from-the required degree ofoligomerization. The hydrohalic acid that is released may then beremoved.

[0020] The addition of a conventional catalyst for the oligomerizationand/or co-oligomerization, such as for example hydrogen chloride, may bedispensed with since it is formed during the reaction of thehalogensilane with alcohol. The chlorosilane may be added dropwise tothe alcohol/water mixture or vice versa.

[0021] The halogenalkyl function may be modified with the followingcompounds:

[0022] with ammonia with separation of ammonium halide for theproduction of the aminoalkylsiloxane oligomers,

[0023] with sodium methacrylate or potassium methacrylate withseparation of sodium or potassium halide for the production of themethacryloxyalkylsiloxane oligomers,

[0024] with sodium polysulfide or sodium sulfide and sulfur or sodiumpolysulfide and sodium sulfide with separation of sodium halide for theproduction of the bis[3-triethoxy-alkyl]polysulfane-siloxane oligomersor bis[3-triethoxy-alkyl]disulfane-siloxane oligomers,

[0025] with ammonia and hydrogen sulfide or ammonium hydrogen sulfidewith separation of ammonium halide, or sodium or potassium hydrogensulfide with separation of sodium or potassium halide for the productionof mercaptoalkylsiloxane oligomers,

[0026] with sodium, potassium or ammonium rhodanide with separation ofsodium, potassium or ammonium halide for the production of thethiocyanatoalkylsiloxane oligomers,

[0027] with sodium azide with separation of sodium halide for theproduction of the azidoalkylsiloxane oligomers.

[0028] For the modification of the halogenalkyl function the alcohol maybe separated.

[0029] The siloxane oligomers according to the invention have theadvantage that they contain functionalized alkyl groups that areavailable for further reactions.

[0030] The siloxane oligomers according to the invention may be used ascoupling agents in rubber mixtures or as building preservative agents.

[0031] The invention also provides rubber mixtures which arecharacterized in that they contain rubber, precipitated silica and/orcarbon black, the siloxane oligomers according to the invention, andoptionally further rubber auxiliary substances.

[0032] For the production of the rubber mixtures according to theinvention natural rubber as well as synthetic rubbers are suitable.Preferred synthetic rubbers are described for example in W. Hofmann,Kautschuktechnologie, Genter Verlag, Stuttgart 1980, and include, interalia

[0033] polybutadiene (BR)

[0034] polyisoprene (IR)

[0035] styrene/butadiene copolymers with styrene contents of 1 to 60 wt.%, preferably 5 to 50 wt. % (E-SBR or L-SBR)

[0036] isobutylene/isoprene copolymers (IIR)

[0037] butadiene/acrylonitrile copolymers with acrylonitrile contents of5 to 60 wt. %, preferably 10 to 50 wt. % (NBR)

[0038] ethylene/propylene/diene copolymers (EPDM)

[0039] as well as mixtures of these rubbers.

[0040] The rubber mixtures according to the invention may containfurther rubber auxiliary products such as, inter alia, reactionaccelerators, reaction retarders, anti-ageing agents, stabilizers,processing auxiliaries, plasticizers, waxes, metal oxides as well asactivators such as triethanolamine, polyethylene glycol and hexanetriol,which are known in the rubber industry.

[0041] The rubber auxiliary substances may be used in conventionalamounts that are governed by, inter alia, the intended use. Conventionalamounts are for example 0.1 to 50 wt. %, referred to rubber.

[0042] Sulfur, organic sulfur donors or radical-forming agents may serveas crosslinking agents. The rubber mixtures according to the inventionmay moreover contain vulcanization accelerators.

[0043] Examples of suitable vulcanization accelerators aremercaptobenzothiazoles, sulfenamides, guanidines, thiurams,dithiocarbamates, thioureas and thiocarbonates.

[0044] The vulcanization accelerators and crosslinking agents may beused in amounts of 0.1 to 10 wt. %, preferably 0.1 to 5 wt. %, referredto rubber.

[0045] The mixing of the rubbers with the filler and the siloxaneoligomers according to the invention, and optionally rubber auxiliarysubstances, may be carried out in conventional mixing equipment such asrollers, internal kneaders and combined mixers/extruders. Normally suchrubber mixtures are formulated in internal kneaders, in which therubbers, the fillers and the siloxane oligomers according to theinvention, and optionally the rubber auxiliary substances, are first ofall mixed in in one or more successive thermomechanical mixing stages at100° to 170° C. In this connection the order of the addition and thetime at which the individual components are added may have a decisiveeffect on the resultant mixture properties. The rubber mixture that isthereby obtained is then normally added to an internal kneader or to aroller at 40-110° C. together with the crosslinking agents and processedinto the so-called raw mixture for the subsequent process steps, such asfor example shaping and vulcanization.

[0046] The vulcanization of the rubber mixtures according to theinvention may take place at temperatures from 80° to 200° C., preferably130° to 180° C., optionally under a pressure of 10 to 200 bar.

[0047] The rubber mixtures according to the invention are suitable forthe production of moulded articles, for example for the production ofpneumatic tires, tire treads, cable sheathings, hoses, drive belts,conveyor belts, roller coatings, tires, shoe soles, sealing rings,profiled sections and damping elements.

[0048] The siloxane oligomers according to the invention have theadvantages of a low release of alcohol in the reaction in rubber and thefact that they contain functionalized alkyl groups for subsequentchemical reactions.

EXAMPLE 1 Reaction of achloropropyltrichlorosilane-propyltrichlorosilane Mixture with Water andEthanol

[0049] 106.7 g of chloropropyltrichlorosilane and 193.6 g ofpropyltrichlorosilane are added as a mixture to a 1 liter capacitythree-necked flask equipped with stirrer, cooler and nitrogen inlettube. A solution of 380 ml of ethanol and 17.2 g of water is addeddropwise within 50 minutes while cooling. The reaction mixture is thenheated for 4 hours under reflux and the hydrogen chloride gas isexpelled. 228.0 g of a clear, pale yellow liquid are obtained afterremoving the excess ethanol. The ratio of propyl radical to chloropropylradical is 2 to 1.

[0050]¹H-NMR (CDCl₃): δ 0.60 (m, 4 H, Si—CH ₂—CH₂—CH₃), 0.75 (m, 2 H,Si—CH ₂—CH₂—CH₂—Cl), 0.95 (t, 6 H, ³J_(H—H)=7 Hz, Si—CH₂—CH₂—CH ₃), 1.20(m, 12 H, CH ₃—CH₂—O—Si), 1.45 (m, 4 H, Si—CH₂—CH ₂—CH₃), 1.85 (m, 2 H,Si—CH₂—CH ₂ 13 CH₂—Cl), 3.50 (m, 2 H, Si—CH₂—CH₂—CH ₂—Cl), 3.80 (m, 8 H,CH₃—CH ₂—O—Si); hydrolyzable chloride: 0.16%.

EXAMPLE 2 Reaction of a chloropropyltrichlorosilane-octyltrichlorosilaneMixture with Water and Ethanol

[0051] 106.7 g of chloropropyltrichlorosilane and 111.8 g ofoctyltrichlorosilane are added as a mixture to a 1 liter capacitythree-necked flask equipped with stirrer, cooler and nitrogen inlettube. A solution of 240 ml of ethanol and 10.7 g of water is addeddropwise within 40 minutes while cooling. The reaction mixture is thenheated for 4 hours under reflux and the hydrogen chloride gas isexpelled. 182.3 g of a clear, colorless liquid are obtained afterremoving the excess ethanol. The ratio of octyl radicals to chloropropylradicals is 1 to 1.

[0052]¹H-NMR (CDCl₃): δ 0.60 (m, 2 H, Si—CH ₂—(CH₂)₆—CH₃), 0.80 (m, 2 H,Si—CH ₂—CH₂—CH₂—Cl), 0.90 (t, 6 H, ³J_(H—H)=7 Hz, Si—CH₂—(CH₂)₆—CH ₃),1.25 (m, 9 H, CH ₃—CH₂—O—Si), 1.3-1.5 (m, 12 H, Si—CH₂—(CH ₂)₆—CH₃),1.85 (m, 2 H, Si—CH₂—CH ₂CH₂—Cl), 3.55 (m, 2 H, Si—CH₂—CH₂—CH ₂—Cl),3.80 (m, 6 H, CH₃—CH ₂—O—Si); hydrolzable chloride: 0.14%

EXAMPLE 3 Reaction of achloropropyltrichlorosilane-hexadecyltrichlorosilane Mixture with Waterand Ethanol

[0053] 106.7 g of chloropropyltrichlorosilane and 74.1 g ofhexadecyltrichlorosilane are added as a mixture to a 1 liter capacitythree-necked flask equipped with stirrer, cooler and nitrogen inlettube. A solution of 180 ml of ethanol and 8.0 g of water is addeddropwise within 50 minutes while cooling. The reaction mixture is thenheated for 4 hours under reflux and the hydrogen chloride gas isexpelled. 145.3 g of a clear, pale yellow liquid are obtained afterremoving the excess ethanol. The ratio of hexadecyl radicals tochloropropyl radicals is 1 to 2.5.

[0054]¹H-NMR (CDCl₃): δ 0.65 (m, 2 H, Si—H ₂—(CH₂)₁₄—CH₃), 0.80 (m, 5 H,Si—CH ₂—CH₂—CH₂—Cl), 0.85 (t, 3 H, ³J_(H—H)=7 Hz, Si—CH₂—(CH₂)₁₄—CH ₃),1.25 (m, 15 H, CH ₃—CH₂—O—Si), 1.3-1.5 (m, 28 H, Si—CH₂—(CH ₂)₁₄—CH₃),1.90 (m, 5 H, Si—CH₂—CH ₂—CH₂—Cl), 3.55 (m, 5 H, Si—CH₂—CH₂—CH ₂—Cl),3.80 (m, 10 H, CH₃—CH ₂—O—Si); hydrolyzable chloride: <0.1%.

EXAMPLE 4 Reaction of the chloropropylsilane-propylsilane co-oligomerswith Hydrogen Sulfide and Ammonia

[0055] 225 g of the co-oligomer from Example 1 in 250 ml of ethanol areplaced in a 1 liter capacity autoclave equipped with stirrer. Afterrendering the contents inert by pumping in nitrogen twice followed byevacuation, 21 g of ammonia and 34 g of hydrogen sulfide are forced intothe autoclave within 30 minutes. After stirring for 12 hours at 120° C.the autoclave is cooled to room temperature and the excessammonia/hydrogen sulfide mixture is blown off by a hydrogen peroxidesolution. After filtering off the precipitated ammonium chloride andremoving the ethanol from the filtrate, 221 g of a clear colorlessliquid are obtained.

[0056]¹H-NMR (CDCl₃): δ 0.60 (m, 4 H, Si—CH ₂—CH₂—CH₃), 0.75 (m, 2 H,Si—CH ₂—CH₂—CH₂—SH), 0.95 (t, 6 H, ³J_(H—H)=7 Hz, Si—CH₂—CH₂—CH ₃), 1.20(m, 12 H, CH ₃—CH₂—O—Si), 1.45 (m, 4H, Si—CH₂—CH ₂—CH₃), 1.85 (m, 2 H,Si—CH₂—CH ₂—CH₂—SH), 2.60 (m, 2 H, Si—CH₂—CH₂—CH ₂—SH), 3.80 (m, 8 H,CH₃—CH ₂—O—Si).

EXAMPLE 5 Reaction of the chloropropylsilane-octylsilane co-oligomerwith Hydrogen Sulfide and Ammonia

[0057] 180 g of the co-oligomer from Example 2 in 200 ml of ethanol areplaced in a 1 liter capacity autoclave equipped with stirrer. Afterrendering the contents inert by pumping in nitrogen twice followed byevacuation, 21 g of ammonia and 34 g of hydrogen sulfide are forced intothe autoclave within 30 minutes. After stirring for 12 hours at 120 ° C.the autoclave is cooled to room temperature and the excessammonia/hydrogen sulfide mixture is blown off by a hydrogen peroxidesolution. After filtering off the precipitated ammonium chloride andremoving the ethanol from the filtrate, 176 g of a clear colorlessliquid are obtained.

[0058]¹H-NMR (CDCl₃): δ 0.60 (m, 2 H, Si—CH ₂—(CH₂)₆—CH₃), 0.80 (m, 2 H,Si—CH ₂—CH₂—CH₂—SH), 0.90 (t, 3 H, ³J_(H—H)=7 Hz, Si—CH₂—(CH₂)₆—CH ₃),1.25 (m, 9 H, CH ₃—CH₂—O—Si), 1.3-1.5 (m, 12 H, Si—CH₂—(CH ₂)₆—CH₃),1.85 (m, 2 H, Si—CH₂—CH ₂—CH₂—SH), 2.60 (m, 2 H, Si—CH₂—CH₂—CH ₂—SH),3.80 (m, 6 H, CH₃—CH ₂—O—Si).

EXAMPLE 6 Reaction of the chloropropylsilane-hexadecylsilane co-oligomerwith Hydrogen Sulfide and Ammonia

[0059] 145 g of the co-oligomer from Example 3 in 150 ml of ethanol areplaced in a 1 liter capacity autoclave equipped with stirrer. Afterrendering the contents inert by pumping in nitrogen twice followed byevacuation, 21 g of ammonia and 34 g of hydrogen sulfide are forced intothe autoclave within 30 minutes. After stirring for 12 hours at 120 ° C.the autoclave is cooled to room temperature and the excessammonia/hydrogen sulfide mixture is blown off by a hydrogen peroxidesolution. After filtering off the precipitated ammonium chloride andremoving the ethanol from the filtrate, 139 g of a clear colorlessliquid are obtained.

[0060]¹H—NMR (CDCl₃): δ 0.65 (m, 2 H, Si—CH ₂—(CH₂)₁₄—CH₃), 0.80 (m, 5H, Si—CH ₃—CH₂—CH₂—SH), 0.85 (t, 3 H, ³J_(H—H)=7 Hz,Si—CH₂—(CH₂)₁₄—CH₃), 1.25 (m, 15 H, CH ₃—CH₂—O—Si), 1.3-1.5 (m, 28 H,Si—CH₂—(CH ₂)₁₄—CH₃), 1.90 (m, 5 H, Si—CH₂—CH ₂—CH₂—SH), 2.6 (m, 5H,Si—CH₂—CH₂—CH ₂—SH), 3.80 (m, 10 H, CH₃—CH ₂—O—Si).

EXAMPLE 7 Reaction of the chloropropylsilane-propylsilane co-oligomerwith Ammonia

[0061] 221 g of the co-oligomer from Example 1 in 250 ml of ethanol areplaced in a 2 liter capacity autoclave equipped with stirrer. Afterrendering the contents inert by pumping in nitrogen twice followed byevacuation, 150 g of ammonia are forced into the autoclave within 30minutes. After stirring for 16 hours at 120° C. the autoclave is cooledto room temperature and the excess ammonia is blown off. After filteringoff the precipitated ammonium chloride and removing the ethanol from thefiltrate, 216 g of a clear pale yellow liquid are obtained.

[0062]¹H-NMR (CDCl₃): δ 0.60 (m, 4 H, Si—CHH ₂CH₂—CH₃), 0.65 (m, 2 H,Si—CH ₂—CH₂—CH₂—NH₂), 0.95 (t, 6 H, ³J_(H—H)=7 Hz, Si—CH₂—CH₂—CH ₃),1.20 (m, 12 H, CH ₃—CH₂—O—Si), 1.45 (m, 4H, Si—CH₂—CH ₂—CH₃), 1.55 (m, 2H, Si—CH₂—CH ₂—CH₂—NH₂), 2.60 (m, 2 H, Si—CH₂—CH₂—CH ₂—NH₂), 3.80 (m, 8H, CH₃—CH ₂—O—Si).

EXAMPLE 8 Reaction of the chloropropylsilane-octylsilane co-oligomerwith Sodium Rhodanide

[0063] 105 g of the co-oligomer from Example 2 and 23 g of sodiumrhodanide in 100 ml of ethanol are placed in a 1 liter capacityautoclave equipped with stirrer. After rendering the contents inert byforcing in nitrogen twice, the contents are stirred for 8 hours at 115°C. under the intrinsic pressure. After cooling to room temperature,filtering off the precipitated sodium chloride and removing the ethanolfrom the filtrate, 108 g of a clear yellow liquid are obtained.

[0064]¹H-NMR (CDCl₃): δ 0.60 (m, 2 H, Si—CH ₂—(CH₂)₆—CH₃), 0.75 (m, 2 H,Si—CH ₂—CH₂—CH₂—SCN), 0.95 (t, 3 H, ³J_(H—H)=7 Hz, Si—CH₂—(CH₂)₆—CH ₃),1.20 (m, 12 H, CH ₃—CH₂—O—Si), 1.3-1.5 (m, 12 H, Si—CH₂—(CHH ₂)₆—CH₃),1.95 (m, 2 H, Si—CH₂—CH ₂—CH₂—SCN), 3.00 (m, 2 H, Si—CH₂—CH₂—CH ₂—SCN),3.80 (m, 8 H, CH₃—CH ₂—O—Si).

EXAMPLE 9 Reaction of the chloropropylsilane-octylsilane co-oligomerwith Sodium Methacrylate

[0065] 102 g of the co-oligomer from Example 2, 30 g of sodiummethacrylate and 50 mg of N,N′-diphenyl-p-phenylenediamine in 100 ml ofDMF are placed in a 1 liter capacity autoclave equipped with stirrer.After rendering the contents inert by forcing in nitrogen twice, thecontents are stirred for 12 hours at 115° C. under the intrinsicpressure. After cooling to room temperature, filtering off theprecipitated sodium chloride, removing the ethanol from the filtrate andrenewed filtration, 112 g of a clear colorless liquid are obtained.

[0066]¹H-NMR (CDCl₃): δ 0.60 (m, 2 H, Si—CH ₂—(CH₂)₆—CH₃), 0.70 (m, 2 H,Si—CH ₂—CH₂—CH₂—O—C(═O)—C(CH₃)═CH₂)), 0.95 (t, 3 H, ³J_(H—H)=7 Hz,Si—CH₂—(CH₂)₆—CH ₃), 1.20 (m, 12 H, CH ₃—CH₂—O—Si), 1.3-1.5 (m, 12 H,Si—CH₂—(CH ₂)₆—CH₃), 1.80 (m, 2 H, Si—CH₂—CH ₂—CH₂—O—C(═O)—C(CH₃)═CH₂),2.00 (m, 3 H, Si—CH₂—CH₂—CH₂—O—C(═O)—C(CH ₃)═CH₂), 3.80 (m, 8 H, CH₃—CH₂——O—Si), 4.15 (m, 2 H, Si—CH₂—CH₂—CH ₂—O—C(═O)—C(CH₃)═CH₂), 5.50 and6.10 (2 s, H Si—CH₂—CH₂—CH₂—O—C(═O)—C(CH₃)═CH ₂).

EXAMPLE 10 Reaction of the Chloropropylsilane-Octylsilane Co-Oligomerwith Sodium Polysulfide

[0067] 101 g of the co-oligomer from Example 2 in 100 ml of ethanol areplaced in a 1 liter capacity flask equipped with stirrer and cooler.After adding 25 g of sodium polysulfide (Na₂S₄) the contents are stirredunder nitrogen for 4 hours at 82° C. After cooling to room temperature,filtering of the precipitated sodium chloride and removing the ethanolfrom the filtrate, 109 g of a viscous, orange liquid are obtained.

[0068]¹H-NMR (CDCl₃): δ 0.60 (m, 2 H, Si—CH ₂—(CH₂)₆—CH₃), 0.75 (m, 2 H,Si—CH ₂—CH₂—S), 0.95 (t, 3 H, ³J_(H—H=)7 Hz, Si—CH₂—(CH₂)₆—CH ₃), 1.20(m, 12 H, CH ₃—CH₂—O—Si), 1.3-1.5 (m, 12 H, Si—CH₂—(CH ₂)₆—CH₃), 1.7-2.0(m, 2 H, Si—CH₂—CH ₂—CH₂—S), 2.7-3.1 (m, 2 H, Si—CH₂—CH ₂—S), 3.80 (m, 8H, CH₃—CH ₂—O—Si).

[0069] Further modifications and variations will be apparent to thoseskilled in the art from the foregoing and are intended to be encompassedby the claims appended hereto.

[0070] German priority application 101 32 942.3 of Jul. 6, 2001 isrelied on and incorporated hrein by reference.

We claim:
 1. A siloxane oligomer represented by the formulae I or II

in which x is an integer from 0 to 1000, y is a number from 1 to 1000,and the substituents R are identical or different and are each a memberselected from the groups consisting of functionalized alkyl groups,(C₁-C₁₈)alkyl, (C₁-C₄)alkoxy, (C₁-C₄)haloalkoxy, phenyl, aryl, aralkyland hydroxy groups, wherein at least one functionalized alkyl group ispresent per oligomer molecule.
 2. The siloxane oligomer according toclaim 1, wherein the functionalized alkyl group is a halogenated alkyl,aminoalkyl, methacryloxyalkyl, mercaptoalkyl, thiocyanatoalkyl orazidoalkyl group.
 3. The siloxane oligomer according to claim 1, whereinthe functionalized alkyl group is a disulfide or polysulfide bridgeS_(x), where x has a value between 2 and 8, which joins twofunctionalized alkyl groups via the disulfide bridge or polysulfidebridge.
 4. The siloxane oligomers according to claim 1, wherein thesiloxane oligomer is an individual compound with a defined molecularweight.
 5. The siloxane oligomer according to claim 1, wherein thesiloxane oligomer is an oligomer mixture with a molecular weightdistribution.
 6. A process for the production of the siloxane oligomeraccording to claim 1, comprising treating a halogenalkyltrihalogensilaneto oligomerization in the presence of alcohol and water and optionallyco-oligomerized with at least one of a (C₁-C₁₈)-alkyl-, phenyl-, aryl-or aralkyl-trihalogensilane and silicon tetrachloride, optionallymodifying a halogenalkyl function in a further step.
 7. The process forthe production of the siloxane oligomer according to claim 6, furthercomprising modifying the halogenalkyl function with ammonia andseparating ammonium halide.
 8. The process for the production of thesiloxane oligomer according to claim 6, further comprising modifying thehalogenalkyl function with sodium methacrylate or potassium methacrylateand separating sodium halide or potassium halide.
 9. The process for theproduction of the siloxane oligomer according to claim 6, furthercomprising modifying the halogenalkyl function with ammonia and hydrogensulfide or ammonium hydrogen sulfide and separating ammonium halide, ormodifying with sodium hydrogen sulfide or potassium hydrogen sulfideseparating sodium halide or potassium halide.
 10. The process for theproduction of the siloxane oligomer according to claim 6, furthercomprising modifying the halogenalkyl function with sodium, potassium orammonium rhodanide and separating sodium, potassium or ammonium halide.11. The process for the production of the siloxane oligomer according toclaim 6, further comprising modifying the halogenalkyl function withsodium azide and separating sodium halide.
 12. The process for theproduction of the siloxane oligomer according to claim 6, furthercomprising modifying the halogenalkyl function with sodium polysulfideor with sodium sulfide and sulfur or sodium polysulfide and sodiumsulfide, and separating sodium halide.
 13. A rubber compositioncontaining the siloxane oligomer according to claim 1 as a couplingagents.
 14. A rubber composition, comprising rubber, at least one of aprecipitated silica and carbon black, and a siloxane oligomer accordingto claim
 1. 15. The rubber composition according to claim 14 wherein therubber is polybutadien, polyisoprene, styrene/butadiene copolymers withstyrene content of 1 to 60 wt. %, isobutylene/isoprene copolymers,butadiene/acrylonitrile copolymer with acrylonitrile content of 5 to 60wt. %, ethylene/proplyene/diene copolymer or mixtures of these rubbers.16. The rubber composition according to claim 14 further comprising atleast one of a reaction accelerator, reaction retarder, anti-ageingagent, stablilizer, processing auxiliary, plasticizer, wax, metal oxide,and activator.
 17. A process for making a rubber composition comprisingmixing a rubber with the siloxane oligomer according to claim 1, afiller and optionally a rubber auxiliary substance in at least onethermomechanical mixing stage at 100 to 170° C., and adding theresulting mixture to an internal kneader or roller at 40 to 110° C.together with a crosslinking agent.
 18. The process according to claim17 further comprising shaping the resulting rubber composition into thedesired article and vulcanizing to obtain a vulcanized rubber article.19. A rubber tire containing the siloxane oligomer of claim
 1. 20. Ashaped rubber article containing the siloxane oligomer of claim 1.